Fan



June 27, 1961 MOORE 2,990,018

FAN

Filed NOV. 13, 1959 INVENTOR Faber-f j, Moore B MgMQ M ATTORNEY,

United States Patent Ofilice 2,990,018 Patented June 27, 1961 2,990,018 FAN This invention relates to fans for use in moving streams of air and similar gaseous fluids in substantially large volumes, and particularly a fan of this character having a construction adapted to the use of light weight materials in the manufacture thereof.

Fans of this character include a hub to which the blades are resiliently and sometimes adjustably connected, such as disclosed in Patent No. 2,471,578, issued to me on May 31, 1949. It is now found desirable to provide a fan having substantially greater flexibility to give better protection to the blades in turbulent fluids, where the blade load fluctuates widely.

Therefore, the principal objects of the invention are to provide a fan of this character having a blade mounting to give greater flexibility and whereby the blades swing freely so that centrifugal force balances out the air loads of lift and drag when the fan is in operation, and to provide a structure to limit drop of the blades when the fan is idle.

Other objects of the invention are to provide a simple and reliable structure particularly adapted for production of light weight materials such as wrought aluminum with a pure aluminum coating to resist corrosion when operating under corrosion creating conditions; to provide a substantially strong and rigid blade and hub structure while providing a resilient connection therebetween; and to provide a highly flexible connection that safely and securely anchors the blades to the hub.

In accomplishing these and other objects of the invention as hereinafter pointed out, I have provided im proved structure, the preferred form of which is illustrated in the accompanying drawing, wherein:

FIG. 1 is a side elevational view of a part of a fan constructed in accordance with the present invention and which, for simplicity and clarity, illustrates the hub with a single blade mounted thereon.

FIG. 2 is a cross section through the flexible mounting, with the section being taken on the line 22 of FIG. I, particularly illustrating the flexible connection feature of the invention.

FIG. 3 is a section on the line 33 of FIG. 1.

FIG. 4 is a fragmentary perspective view showing the hub end of one of the blades and parts of the pivotal connection shown in disassembled, spaced relation.

FIG. 5 is a perspective view of one of the clevis members that are secured to the hub.

FIG. 6 is a cross section through the flexible connection, taken on the line 6-6 of FIG. 2.

FIG. 7 is a diagrammatic front view of the fan illustrating the drag load.

FIG. 8 is a diagrammatic side view illustrating lift load.

Referring more in detail to the drawing:

1 designates a fan constructed in accordance with the present invention and which includes a hub 2 carrying a plurality of generally radially directed blades 3 that are mounted on the hub 2 by flexible connections 4. The hub 2 includes a main part 5 having a disk portion 6, a laterally directed annular flange 7 projecting from one side thereof, and an axial collar 8 projecting from the opposite side. The collar 8 has an axial bore 9 by which the hub is mounted upon and suitably keyed to an operating shaft, not shown. The hub 2 also includes a ring part 10 conforming in inner and outer diameter to the inner and outer diameter of the flange 7 and which is fixed thereto by bolts 11. The flange 7 and facing side of the ring part are provided with substantially semicircular notches 12 and 13, circumferentially spaced about the periphery thereof and internally threaded as at 14 to mount clevises 15. The number and spacing of the notches 12 and 13 depend upon the number of blades to be mounted upon the hub.

The clevises 15 are best illustrated in FIG. 5, and each includes a yoke 16 having a disk shaped base 17 and extending from the base at one side thereof are diametrically spaced apart cars 18 and 19. The cars 18 and 19 have openings 20 and 21 for passing a fastening or pivot member 22, later to be described.

Extending from the opposite side of the base 17 is an externally threaded stem 23 having a diameter to be turned into the internally threaded notches in the parts of the hub and to cooperate with the base in providing an annular shoulder 24. The notches 12 and 13 are so formed in the hub that when the stems 23 are turned therein, the ring part 10 of the hub is slightly spaced from the flange 7 to provide a gripping action on the stems of the clevises when the bolts 11 are tightened, to thereby retain the ears of the yoke at the proper angle relatively to the rotational direction of the fan to maintain the desired pitch for the fan blades 3.

The fan blades 3 may be of a suitable construction and contour to effect efficient movement of the air, as determined by engineering practice. The fan blades also have shanks 25. The shanks 25 are formed by a plurality of angle members 26, each preferably composed of wrought aluminum and having a pure aluminum coating. The angle members 26 are arranged in spaced apart assemblies 27 and 28, wherein legs 29 of two of the angle members in each assembly are in lapping relation and min forced by a plate 30 to provide relatively rigid webs 31 of the angle assemblies 27 and 28. The other and shorter legs 33 of the angles project outwardly and laterally from the webs 31 for attaching plate assemblies 34 and 35 to provide a substantially rigid boxlike cross section, as best illustrated in FIGS. 2, 3 and 4. The legs 29, composing the webs, are securely connected together as by spot welding or rivets, as indicated at 36, and the plate assemblies 34 and 35 are secured to the legs 33 by similar fastening means, such as rivets 36, as best illustrated in FIG. 2. The outer ends of the stems 23 as thus constructed are suitably shaped for attachment to the fabricated shell 37 or skin of the impeller portions of the blades. The inner ends and the plate assemblies are shaped to provide stops 38 (FIG. 1) for contact with the base portions 17 of the clevises and/ or the periphery of the hub, to limit swinging movement of the blades.

In order to flexibly mount the shanks 25 in the clevises 17 in accordance with the present invention, the web assemblies 31 and 32 are provided with openings 39 and 40 for mounting therein the reduced ends 41 of a thimble 42 that extends transversely between the web assemblies with annular shoulders 43 thereon abutting the inner faces of the web assemblies, as shown in FIG. 2. The thimble 42 thus described is suitably anchored in the openings 39 and 40 of the webs, for example by expanding the ends to prevent turning thereof. Extending through the thimble is a bushing or mounting sleeve 44 of smaller diameter than the inner diameter of the thimble 42 to accommodate therebetween a resilient sleeve 45, such as rubber or the like, and which may be suitably bonded to the sleeve 44 and/or thimble 42, whereby the sleeve 44 is resiliently anchored in the thimble 42 and oscillative movement of the sleeve within the thimble is provided through the flexibility of the resilient material. However, it is preferable that the resilient sleeve 45 should seat snugly within the resilient thimble and around the bushing 44. It is obvious that with this construction the bushing 44 is resiliently retained in the thimble and may have limited freedom of movement in the rotary direction of the fan.

' The ends of the mounting sleeve or bushing 44 project from the ends of the thimble and are convexly curved as at 46 to correspond with the inner curvature 47 of the ears i8 and 19 of the clevises and prevent turning of the mounting sleeve therein when the blades are assembled in the hub of the fan.

The pivot member 22 extends through the bore 48 of the mounting sleeve 44 and through the registering oper1 ings 2-9 and 21 of the ears. The ends of the pivot member 22 project from the outer sides of the ears of the clevises and threads 49 and Si? are provided for applying jam nuts 52 and 53, washers 54 and 55 being preferably inserted between the jam nuts and the outer sides of the ears, as shown in FIG. 2. One jam nut may be fixed to its end of the pivot member 22 by welding or the like, so that it in effect constitutes a head in the manner of a bolt, while the jam nut at the opposite end is adapted to be tightened for drawing the parts together in their assembled relation, as best shown in FIG. 2.

When the parts are assembled, the diameter of the fan may be adjusted to an over or under sized throat by loosening the bolts 11 and turning the stems 23 into or out of the hub, as the case may require, after which the bolts are retightened to maintain the adjustment.

The clevises are also set so that the axis of each pivot member 22 is positioned substantially at right angles to the resultant forces of the lift and drag. The lift and drag might vary with turbulence of the fluid stream, but the resultant of the two forces remains substantially the same, so that after the angle of the pivot member is fixed, it remains the same. For example, in the position illustrated the angle of the pivot member and mounting sleeve is about 10 relatively to a plane that extends at right angles to the axis of rotation. The center of gravity of each blade 3, designated CG. in FIG. 7, is located in lag, that is, on the retractive side of a radial line a extended from the center of the fan hub, so that torque exerted by the driver of the fan is converted to tension acting along the axis b of the fan blade. Thus the pivotal connection of point to the hub pulls the blade in an endwise direction and without producing bending forces under the drag load.

The lift load acting on the front of the blade as indicated in FIG. 8 is counteracted by centrifugal force which tends to hold the axis of the blade in the plane indicated by the center line d extending generally transversely of the axis of hub rotation. If desired, the angle of the blades might be adjusted by turning the clevises within the hub.

It is obvious that the blades of the fan have pivotal movement on the hub by reason of the resilient sleeve 45. Consequently, the blades are free to adjust themselves when the fan is in operation and thereby eliminate tendency of the blades to bend and break under drag and lift loads, particularly when operating under turbulent conditions.

With the above described blade mounting, the blades have relatively free swinging movement under centrifugal force to balance out loads of lift and drag when the fan is in operation. The drop of the blades from their operative positions is limited when the fan is stopped by the ends of the shanks engaging the bases of the clevises. If it is desired, the space between the hub and inner edges of the blades may be closed by attaching segments (not shown) to studs 56 that are carried by the plate assembly 35 (FIG. 1).

From the foregoing, it is obvious that I have provided a fan wherein the blades have substantially free swinging movement and a greater resilient action under operative conditions by reason of the relation of the resilient sleeve to the transverse pivotal member 22. It is also obvious that I have provided a simpler and less expensive construction, and which is especially adapted to the production of fans from light weight materials while utilizing a strong and rigid assembly of the parts of the hub, clevises, and shanks of the blades.

What I claim and desire to secure by Letters Patent is:

1. In a fan of the character described, a hub, 21 blade having a shank, and means pivotally connecting the shank on the hub for pivotal movement of the blade on an axis transverse of the axis of rotation of the hub for centrifugal force to balance air loads of lift and drag when the fan is in operation, and said blade having a center of gravity in lag from a radial line extending through the axis of rotation and said pivotal connection being in advance of said line to hold the shank of the blade in tension during rotation of the fan.

2. In a fan, a fan blade having a shank including spaced apart angle member assemblies, each including two angles with legs thereof in interlapping contact and reinforced by a backing plate, the other of said legs of the angles extending outwardly, and plates connecting the latter legs of the assemblies to provide a shank of boxlike cross section.

3. In a fan, a fan blade having a shank including spaced apart angle member assemblies, each including two angles with legs thereof in interlapping contact and reinforced by a backing plate, the other of said legs of the angles extending outwardly, plates connecting the latter legs of the assemblies and in cooperation with the overlapping legs to provide a shank of boxlike section, said interlapping of the angles and said backing plate having registering openings extending therethrough, a thimble extending across said boxlike section and having ends thereof fixed within said openings and secured from rotation therein, a resilient sleeve within the thimble, and a mounting sleeve extending through the resilient sleeve.

4. In a fan of the character described, a hub having a main part and a ring part each having registering radially disposed internally threaded notch portions, a clevis having a threaded stem engaging the threads of the notches, said clevis also having spaced apart ears, fastening devices extending through said parts of the hub to draw said parts together in clamping contact with the stem of the clevis with said ears being generally transversely of the hub, a fan blade having a shank, a thimble carried by the shank, a resilient sleeve in the thimble, a mounting sleeve extending coaxially through the resilient sleeve, and a clamping member extending through the mounting sleeve and having ends abutting the ears of the clevis for preventing rotation of the mounting sleeve so that the thimble of the fan blade turns on the mounting sleeve in a direction generally transversely of the rotational axis of the hub by position of the ears on said hub, and said shank having a part adapted to contact a part on said hub for limiting pivotal movement of the fan blade.

5. In a fan of the character described, a hub, a fan blade having a shank, a thimble carried by the shank and having an axis extending transversely of the rotational axis of the blade, a mounting sleeve, a resilient sleeve within the thimble for resiliently supporting the thimble on the mounting sleeve, and a clamping member extending through the mounting sleeve for securing the mounting sleeve from turning on the hub, whereby the thimble moves on the mounting sleeve by the resiliency of the resilient sleeve, said shank having a part adapted to contact a part on the hub for limiting movement of the fan blade relatively to the radial line extending through said axis of rotation.

6. In a fan of the character described, a hub, a fan blade having a shank, a thimble carried by the shank and having an axis extending transversely of the rotational axis of the blade, a mounting sleeve, a resilient sleeve within the thimble for resiliently supporting the thimble on the mounting sleeve, and a clamping member extending through the mounting sleeve for securing the mounting sleeve from turning on the hub, whereby the thimble moves on the mount-ing sleeve by the resiliency of the resilient sleeve to provide a piYQtfll. QQI QQQtiQn for the fan blade so that centrifugal force balances air loads of lift and drag when the fan is in operation, and said blade having a center of gravity in lag from a radial line extending through the axis of rotation of the hub and said pivotal connection being in advance of said line to hold the shank of the blade in tension during rotation of the fan.

7. In a fan, a fan blade having a shank including spaced apart angle member assemblies, each including two angles with legs thereof in interlapping contact and reinforced by a backing plate, the other legs of the angles extending outwardly to provide flanges, plates connecting said flanges of the angle member assemblies and cooperating with the interlapping legs to provide a shank of boxlike section, said interlapping legs of the angles and said backing plates having openings extending therethrough, a thimble extending across said boxlike section and having ends thereof fixed within said openings against rotation therein, a resilient sleeve Within the thimble, a mounting sleeve extending through the resilient sleeve, a hub, a clevis fixed to the hub and having spaced apart ears engaging the ends of the mounting sleeve therebetween, and a fastening member extending through the mounting sleeve and through the ears for clamping the ears to the ends of the mounting sleeve, said thirnble being movable on the mounting sleeve by the resiliency of said resilient sleeve.

8. In a fan, a fan blade having a shank including spaced apart angle member assemblies, each including two angles with legs thereof in interlapping contact and reinforced by a backing plate, the other legs of the angles extending outwardly to provide flanges, plates connecting said flanges of the angle member assemblies and cooperating with the interlapping legs to provide a shank of boxlike section, said interlapping legs of the angles and said backing plates having openings extending therethrough, a thirnble extending across said boxlike section and having ends thereof fixed within said openings against rotation therein, a resilient sleeve Within the thimble, a mounting sleeve extending through the resilient sleeve, a hub, a clevis fixed to the hub and having spaced apart ears engaging the ends of the mounting sleeve therebetween, and a fastening member extending through the mounting sleeve and through the ears for clamping the ears to the end of the mounting sleeve, said thimble being movable on the mounting sleeve by the resiliency of said resilient sleeve to provide a pivotal connection so that centrifugal force balances air loads of lift and drag when the fan is in operation, and said blade having a center of gravity offset from a radial line extending through the axis of rotation and said pivotal connection being in advance of said line to hold the shank of the blade in tension during rotation of the fan.

References Cited in the file of this patent UNITED STATES PATENTS 1,802,648 Heath Apr. 28, 1931 1,924,349 Charavay Aug. 29, 1933 2,259,247 Dornier Oct. 14, 1941 2,436,087 Benson Feb. 17, 1948 

